By now you probably know that a Milestone 3 build of Windows 8 has been leaked to the web. The leaked build 7989 (x64) includes a new Betta fish boot screen, new wallpaper, improved Portable Workspace Creator, and some other changes.
If you are running Windows 7, here is a nice way to get Windows 8 pre-beta Microsoft confidential watermark and build string watermark on your Windows 7 desktop.
You can get 7989 build string watermark and Microsoft Confidential text on your Windows 7 desktop with the help of a Rainmeter skin. As you can see in the below snapshot, the watermark is simply perfect.
How to install and enable the watermark skin:
Step 1: Download and install Rainmeter. Skip this step if you have already installed Rainmeter software.
Step 2: Download Windows 8 watermark skin from here and extract the contents of the zip file to C:\Users\YourUserName\Documents\Rainmeter\Skins.
Step 3: Run Rainmeter software. Right-click on the Rainmeter icon in the system tray and click Refresh all.
Step 4: Right-click on the Rainmeter tray icon and then go to Configs, W8, and select Watermark and Watermark MS Conf options.
Step 5: You can now move the watermark on your desktop to bottom right corner.
Also check out how to get Windows 8 Start screen in Windows 7 guide.